Drill collar



Aug, 24, 1937.

J. c. WRIGHT DRILL COLLAR Filed Oct. 2, 1936 3 Sheets-Sheet 1 19%;? Elia/we J. C. WRIGHT Aug. 24, m7.

DRILL COLLAR Filed Oct. 2, 193s 3 Sheets-Sheet 2 5379* 1 may 9260 7' J. c. WRIGHT 2,09%22 DR I LL C OLLAR Filed 00%.. 2, 1936 3 Sheets-Sheet 3 Patented Aug. 24, 1937 UNHTE STATE awn 15 Claims.

This invention relates to rotary well drilling equipment and relates more particularly to a drill collar for use in a rotary well drilling string. A general object of this invention is to provide an improved and particularly efiicient drill collar that is safe and dependable in operation.

In the rotary method of well drilling a drill collar is usually interposed between the drilling string and the drilling tool. A drill collar is a tubular length of steel having a substantial thickness to impose additional weight on the bit and to lend rigidity to the lower portion of the drilling string for the transmission of the torque. Where hard earth formations are encountered in a well it has been found necessary to form the drill collar of great length to impose sufiicient weight on the tool or bit. A drill collar of great length has certain disadvantages, for example, its upper end has a tendency to fall over against the wall of the bore and cause the deviation of the bit. Heretofore it has been found impractical to increase the weight of a drill collar by increasing its diameter as it has been deemed necessary to leave suiiicient clearance between the drill collar and the wall of the well bore to receive a washover pipe in the event the bit and drill collar are caught or lost in the well. According- 1y, where additional weight has been required it has been the practice to increase the length of the drill collar even though a long drill collar has numerous disadvantages.

Another object of this invention is to provide a drill collar of substantial weight whose weight is concentrated immediately above the drilling tool to resist the forces tending to cause deviation of the drilling tool.

Another object of this invention is to provide a drill collar of minimum length and maximum weight.

Another object of this invention is to provide a drill collar of substantial diameter to have only slight clearance in the well bore to act as a bearing guide and stabilizer for the drilling tool.

Another object of this invention is to provide a heavy drill collar of large diameter that may m be easily loosened or freed for recovery from the well in the event the drill collar and bit become caught or lost in the well.

Another object of this invention is to provide ()0 a heavy drill collar of large diameter that has provision for conducting circulation fluid to its lower end to discharge into the well bore in the event the usual circulation passage is obstructed or ineiiective due to breaking of the drilling string 55 and sanding up of the bit and drill collar. The

drill collar of the present invention is adapted to receive fluid from a fishing string and discharge the fluid into the well bore at its lower end to loosen or Wash away mud or sand that may accumulate about it whereby the drill collar and 5 bit may be fished or recovered from the Well.

Another object of this invention is to provide a drill collar comprising an inner part and an outer part that may have relative longitudinal and/or rotary movement to efiect the loosening and 10 freeing of the outer part from accumulations of sand and mud to facilitate the easy recovery of the drill collar and drilling tool in the event they become caught in the well.

Another object of this invention is to provide a drill collar of the character mentioned that may be employed or operated to produce a jarring action to free or loosen the drilling tool.

Another object of this invention is to provide an attachment for a typical drill collar that materially adds to its weight and effectiveness and gives it the characteristics and capabilities mentioned above.

A further object of this invention is to provide a drill collar in which the wear receiving parts may be easily and quickly replaced or reconditioned.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applications of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. l is a side elevation of one form of drill collar provided by the invention. Fig. 2 is an enlarged side elevation of the drill collar illustrated in Fig. 1 showing the outer member in longitudinal cross section. Fig. 3 is a fragmentary longitudinal detailed sectional view illustrating the washover pipe connected with the outer member. Fig. 4 is an enlarged transverse detailed sectional view taken as indicated by line 4-4 on Fig. 1. Fig. 5 is an enlarged transverse detailed sectional View taken as indicated by line 5-5 on Fig. 3. Fig. 6 is a side elevation of another embodiment of the invention illustrating the outer member in longitudinal cross section. Fig. '7 is a transverse detailed sectional view taken as indicated by line ll on Fig. 6. Fig. 8 is a fragmentary longitudinal detailed sectional view of still another form of the invention with a portion in side elevation, and Fig. 9 is a transverse detailed sectional view taken as indicated by line 9-9 on Fig. 8.

The drill collar of the present invention illustrated in Figs. 1 to 5, inclusive, of the drawings, includes generally an inner member ID to be connected in a drilling string S and an outer weight member II surrounding the inner member In and supported on the inner member II].

The inner member IE! is the torque and force transmitting element of the drill collar. In practice the inner member IE] may be a typical drill collar of suitable length and of suificient diameter to have the required rigidity and strength. The inner member I0 is an elongate cylindrical part that may be substantially uniform in diameter throughout its length. A central longitudinal fluid passage I2 extends through the inner member II] from one end to the other for conducting the drilling fluid during drilling operations. The inner member ID is of substantial wall thickness to have the desired strength and to be of substantial weight. A tapered threaded socket I3 is preferably provided in the upper end of the inner member ID. The invention provides a spe-v cial connecting member or sub I4 for connecting the upper end of the inner member It! with the drilling string S. The sub I4 has a pin I5 threaded in the socket I3 and may have a pin I 6 threaded into a coupling section I 'I on the lower end of the string S. Circumferentially spaced ears or lugs I8 are provided on the sub I4 and project outwardly or radially from the sub. The lugs I8 have flat substantially horizontal lower ends and form anvil abutments for use in jarring as will be hereinafter described.

A special sub I9 is provided for connecting the lower end of the inner member III with a bit B or other part of the drilling string. The sub I9 is provided with a pin 20 threaded into a socket 2I in the lower end of the inner member II). In accordance with the invention the sub I9 is considerably larger in diameter than the inner member I0 so that its upper end forms an annular upwardly facing shoulder 22 at the lower end of the inner member. The shoulder 22 is preferably fiat and substantially normal to the longitudinal axis of the drill collar. The sub I9 may have a socket 23 in its lower end receiving a pin 24 on the upper end of the bit B. In the drawings I have illustrated a typical fish-tail bit B connected with the drill collar, it being understood that the drill collar may be employed with various forms and types of drilling tools. A plurality of circumferentially spaced ribs or blades 25 project radially from the sub I9. The blades 25 may engage the wall of the well bore to assist in stabilizing the bit B and the lower portion of the drill collar. The upper and lower ends of the blades 25 may be bevelled away, as illustrated.

The outer member II forms the weight element and stabilizing element of the device. The outer member I I also serves as a washover pipe to conduct fluid for fishing operations as will be subsequently described. The outer member II is an elongate tubular part surrounding the inner member I0. In the form of the invention being described the outer member II is integral or one piece. The outer member II is formed of steel or other material having a relatively high specific gravity. In the preferred construction the outer member II is of sufficient length to surround the major portion of the inner member III. The outer member I I surrounds the inner member ID with some clearance leaving an annular fluid passage 26. The outer member I I is proportioned to lit the well bore with only slight clearance to permit the necessary circulation of fluid through the bore. Being proportioned in this manner the outer member I I acts as a bearing or stabilizer for the drilling string adjacent or immediately above the bit B. The outer member II has substantial wall thickness and a substantial length and, therefore, adds materially to the weight of the drill collar.

A replaceable clutch part 21 is provided on the lower end of the outer member II to support it on the shoulder 22. The part 21 may have a pin 28 threaded into an opening or socket 29 in the lower end of the outer member II. The threads of the pin 28 and socket 29 are preferably lefthand threads. The clutch part 21 is preferably of the same external diameter as the outer member II and fits about the inner member I0 rather snugly to centralize and stabilize the outer member relative to the inner member. The lower end of the clutch part 21 is flat and rests on the shou1 der 22 to support the outer member II. Means is provided for transmitting rotation between the members It and I I. In the preferred structure illustrated this means includes clutch lugs 30 on the shoulder 22 cooperating with correspondingly shaped notches 3| in the lower end of the clutch part 21. When the clutch part 2'! rests on the shoulder 22 its notches 3| receive the lugs 39 so that the outer member II turns with the inner member Ill.

Means is provided on the upper end of the outer member II to receive and connect with a washover pipe 32. The upper end of the outer member II is provided with a tapered pin 34 carrying a heavy thread. The washover pipe 32, which may be employed for fishing and for freeing the drill collar and bit B from the accumulations of mud and sand, is adapted to be run downwardly over the string S. A coupling 35 is provided on the lower end of the washover pipe 32 and has a socket 35 in its lower end adapted to receive the pin 34. A heavy thread is provided on the wall of the socket 33 to mate with the thread on the pin 34 as best illustrated in Fig. 3 of the drawings. The threads of the pin 34 and the socket 36 are preferably right-hand threads. When the coupling 35 of the washover pipe 32 is threaded on the pin 34 the lower end of the washover pipe 32 is in direct communication with the passage 26 through the outer member I I. The outer member I i is provided with ports 38 for discharging the fluid from the passage 26 into the well bore. The ports 38 are preferably located a short distance above the lower end of the outer member II as illustrated in the drawings. It is to be understood that the washover pipe 32 is normally disconnected from the outer member I I and does not form a part of the drill collar during the drilling operation. The coupling 35 on the lower end of the washover pipe 32 may be provided with radially and downwardly projecting fingers 39 for clearing sand and mud from around the pin 34 when the washover pipe 32 is to be connected with the outer drill collar member II.

During operation the drill collar is assembled or connected in the drilling string as illustrated in Figs. 1 and 2 of the drawings. The string S is rotated and fed downwardly in the usual manner to operate the bit B. The thick walled inner member ID and the thick walled outer member II are of great weight so that the drill collar imposes a substantial feeding weight or pressure on the bit B. In practice the weight of the drill collar may be suificient to feed the bit B into the earth formation without applying the weight of the drilling string S on the bit B so that the drilling string or the major portion of the drilling string may be suspended from its upper end during the drilling operation. It will be observed that the weight of the improved drill collar is concentrated in a minimum vertical distance or height immediately above the bit B to cause the bit B to drill a straight bore and to resist the forces tending to divert the bit. The outer member I I and the blades 25 serve to guide and stabilize the bit and the lower end of the drilling string. The outer member H serves as a bearing at the lower end of the drilling string to prevent excessive wobbling and lateral movement of the bit B. The usual circulation fluid is pumped downwardly through the string S to flow through the passage l2 and discharge from the bit B. The fluid returns upwardly through the Well bore passing around the outer member I I of the drill collar. The inner member ID transmits the torque or driving forces to the bit B. The inner member ii) is rigid to dependably transmit these forces. The outer member l l merely rests on or imposes its weight on the inner member i9 and bit B through the sub i9 and is not subjected to any of the driving torque. The clutch lugs 3!! cooperate with the notches St to form a rotative driving connection between the members Ill and H. The weight of the outer member H is sufiicient to properly hold the lower end of the clutch part 21 on the shoulder 22. The clutch part 2'! and the sub iii are the only parts of the drill collar subject to Wear due to vibration of the parts. The clutch part 21 and the sub i9 may be readily replaced when worn.

In the event the bit B and drill collar become caught or sanded in the well bore or the string S parts or breaks, the wash pipe 3?. carrying the coupling 35 is lowered into the well. The

40 Wash pipe 32 is adapted to pass downwardly over the string S or the portion of the string S remaining in the well. The wash pipe 32 is lowered until the coupling 35 reaches the pin 3% on the upper end of the member H. The wash pipe 32 is rotated to thread the coupling on the pin 34. The fingers 39 are operable to clear the mud and sand away from the pin 3 when the coupling is to be threaded on the pin. The weight of the outer member H and the engagement of 50 the lugs 30 in the notches 3! hold the outer mem- 55 tically with the wash pipe or may be rotated with the wash pipe, or both. Further, when the wash pipe 32 is connected with the outer member H its interior is in direct communication with the passage 26. By moving the outer member ii by means of the wash pipe 32 it may be possible to free the drill collar and bit for removal from the well on the wash pipe. Water or circulation fluid may be pumped downwardly through the wash pipe 32 to flow through the passage 26 and discharge from the ports 38. This fluid discharging from the ports 38 flows upwardly around the outer member Ii to cut away the accumulations of mud and sand about the outer member. The water or fluid may be pumped through the wash pipe 32 to free the outer member 5! with or without movement of the outer member. The outer member ll providing the annular passage 26 serves as a washover pipe to conduct the water or fluid to the lower end of the drill collar to free the drill collar when the regular circulation passage through the drilling string is obstructed or disconnected from its source of supply,

If the reciprocation or rotation of the outer member II and the discharging of water or fluid from the ports 38 frees the outer member to permit the drill collar and bit to be withdrawn the assembly may be removed from the well on the wash pipe 32. In some instances the bit B may be tightly caught or lodged in the well and it may be deemed advisable to impart a jarring action to the bit to free it. The wash pipe 32 may be raised suddenly to bring the upper end of the pin 3 into jarring contact with the lower ends of the lugs l8. This jarring operation may be repeated until the bit B is freed or loosened. From the above it will be seen that the outer member ll of the drill collar in addition to giving the drill collar additional weight serves as a fishing attachment to facilitate the fishing of the drill collar and bit from the well. The outer member i i may serve as a Wash over pipe to conduct the flushing fluid to a point adjacent the bit 13 and may be moved to loosen the accumulations of mud and sand and to impart a jarring action to the bit B.

Figs. 6 and 7 of the drawings illustrate a form of the invention embodying a sectional outer member H The inner member l6), and the subs I4 and i9 may be the same as the corresponding elements of the previously described form of the invention.

The outer member H of the drill collar illustrated in Figs. 6 and 7 comprises a plurality of tubular sections 533. The several sections 50, with the exception of the uppermost section and the lowermost section, may be identical. The sections 58 are tubular members having relatively thick walls and formed of steel or the like. Each of the sections 50, with the exception of the lowermost section, has a tapered socket 5! in its lower end. Each section 59, with the exception of the uppermost section, has a tapered pin 52 on its upper end fitting the socket 5i in the adjacent section. The pins 52 may be slotted at 53 to accurately or tightly fit the sockets 5i when the sections 52 are assembled. Dowel pins 52 may be arranged through openings in the telescoping parts of the sections 50 to lock them against rclative movement. The outer member ii may be of substantially the same wall thickness as the above described member ii and surrounds the inner member 50 with substantial clearance. To facilitate the assembling and handling of the sections 513 it may be preferred to arrange them around a carrier tube St. The tube 6?] is adapted to surround the inner member with clearance to leave a fluid passage 28 The tube 55 may be welded to the lowermost section 56 at 6! and to the uppermost section 563 at 62 whereby the assembly of sections 56' may be handled as a unit. Ports :38 are provided in the lower portion of the lowermost section 5B to discharge the fluid passed downwardly through the passage 26 The lowermost section '5 may be provided with notches 3P in its lower end to receive the clutch lugs 38 on the sub H). A pin 35 is provided on the upper end of the uppermost section 553 and carries a heavy thread to cooperate with the thread on the coupling 35 of the washover pipe.

The drill collar illustrated in Figs. 6 and 7 operates in the same manner as the previously described form of the invention. The sectional outer member I l is easy to handle and assemble and may be made up in various lengths to adapt it for use on various typical drill collars.

Figs. 8 and 9 illustrate a modified or alternative construction for the lower portion of the drill collar. The construction illustrated in Figs. 8 and 9 may be embodied in the form illustrated in Figs. 1 to 5, inclusive, or in the form illustrated in Figs. 6 and 7. As shown, the construction of Figs. 8 and 9 includes an inner member ID identical with the above described member [0 and an outer member ll identical with the above-described outer member H. A special sub l9 is connected with the lower end of the inner member ID. The sub l9 has a pin 10 on its upper end threaded into thesocket 2| in the lower end of the inner member Hi. The upper portion 'H of the sub I9 may extend upwardly into the outer member I l and is of substantially the same diameter as the member Hi. The sub 19* is enlarged intermediate its ends to have a tapered threaded pin 12. The pin 72 faces upwardly and carries a lefthand thread. Projecting lugs orwings 13 may be provided at the base of the pin 12. The lower portion of the sub 19 is smaller in diameter than the pin 12 and has a threaded socket 23 receiving the pin 24 of the bit B. The lower end of the outer member ll carries the clutch part 21 described above. In accordance with the invention, as illustrated in Figs. 8 and 9, a releasable and replaceable clutch part I5 is threaded on the pin '12. The clutch parts 21 and 15 have meshing teeth 16 for transmitting rotation between the members l0 and H. The reduced portion ll of the sub l9 extends upwardly through the clutch parts 15 and 2i and has a plurality of spaced longitudinal grooves TI. The

1 grooves T! are adapted to carry the flushing fluid downwardly from the lower end of the space 26 to the meshing teeth 16 where it may discharge into the well bore. The clutch part 15 may be of the same external diameter as the part 21 and the member I l.

The construction illustrated in Figs. 8 and 9 has the same mode of operation as the previously described forms of the invention except that the outer member I i may be backed off or unthreaded in the event that it cannot be easily raised. The lefthand threads of the pin 12 and the clutch part 15 are not loosened during drilling because the drag of the outer part H on the wall of the well tends to tighten the lefthand threads. The washover pipe 32 may be connected with the outer part H by the coupling 35 without prematurely loosening the threads of the part I5 and pin 12 as the threads of the socket 36 and the pin are right-hand threads. When the washover pipe 32 has been properly connected with the outer part ll it may be rotated to unthread the part 15 from the pin 12 to free the outer member H for free rotation and vertical movement. Following this freeing of the outer part I I it may be moved by means of the wash pipe 32 so that the flushing fluid may wash away the accumulation of mud about it.

Having described only typical preferred forms and applications of the invention I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. A drill collar for connection in a tubular drilling string including, an inner member to be connected in the string for the transmission. of torque and having a passage for conducting fluid during drilling, and an integral tube surrounding the inner member with clearance to leave a passage for conducting fluid when the first named passage is inoperative and having a coupling means formed on its upper end for connecting with a wash-over pipe passed downwardly over the string.

2. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string between adjacent parts thereof, a weight element supported on the member for longitudinal movement thereon, and a projection on the inner member engageable by the element to impart an upward jarring action to the string.

3. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string as a rigid part thereof, a shoulder on the member, a projection on the member above the shoulder, and a weight element normally supported on the shoulder and movable on the member tojar against the projection.

4. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string as a rigid part thereof, a shoulder on the member, a projection on the member above the shoulder, and a tubular weight element surrounding the mem ber where it is normally supported on the shoulder and movable vertically to jar against the projection.

5. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a shoulder on the inner member, a thick walled tube of steel surrounding the inner member and supported on the shoulder, there being a space between the inner member and the tube for passing fluid, the tube having a discharge port in its lower portion communciating with the space, and a coupling on the upper end of the tube for connecting with a pipe for conducting fluid downwardly to said space.

6. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a replaceable sub connecting the lower end of the inner member in the string, a tubular weight element surrounding and shiftable longitudinally on the inner member, and a replaceable part on the lower end of the element resting on the sub.

'7. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string as a rigid part thereof, a shoulder on the inner member, a thick walled tube of steel shiftably surrounding the inner member and supported on the shoulder, a stop on the inner member spaced above the shoulder to limit the upward movement of the tube on the inner member, the tube being materially larger in diameter than the string to form a bearing stabilizer in the well, and coupling means on the upper end of the tube for connecting with a wash-over pipe.

8. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a replaceable sub connecting the lower end of the inner member in the string, stabilizing lugs on the sub for engaging the wall of the well, a tubular weight element surrounding and shiftable on the inner member, and a replaceable part on the lower end of the element resting on the sub.

9. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a replaceable sub connecting the lower end of the inner member in the string, a tubular weight element surrounding and shiitable on the inner member, a replaceable part on the lower end of the weight element resting on the sub, and clutch surfaces on the sub and part preventing relative turning between the inner member and the weight element releasable by relative longitudinal movement between the member and element.

10. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a tubular weight element surrounding and supported on the inner member, the element including, tubular sections having telescopically assembled end portions, and coupling means on the upper end of the tubular element for connecting with a washover pipe.

11. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a tubular weight element surrounding and supported on the inner member, the element including, tubular sections having telescopically assembled end per-- tions, and means for securing the sections against separation, and coupling means on the upper end of the element for connecting with a wash-over pipe.

12. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, and a tubular weight element surrounding and supported on the inner member, the element including, tu bular sections, one section having a tapered socket in its end, and a tapered pin on the adjacent section cooperating with the socket.

13. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a thick walled tubular weight element surrounding and supported on the inner member, the element comprising a plurality of superimposed longitudinal sections, and coupling means on the upper end of the element for connecting with a wash-over pipe.

14. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a replaceable sub connecting the lower end of the inner member in the string, a tubular weight element surrounding and shiftable on the inner member, a replaceable part on the lower end of the weight element resting on the sub, left hand threads connecting the replaceable part with the weight element, clutch surfaces on the sub and part releasable by relative longitudinal movement between the member and element, and a right hand thread on the upper end. of the weight element adapted to mate with a thread on the fishing string whereby the weight element may be backed off by the string.

15. A drill collar for connection in a drilling string including, an inner torque transmitting member to be connected in the string, a replaceable sub connecting the lower end of the inner member in the string, a tubular weight element surrounding and shiftable on the inner member, a clutch part on the lower end of the outer member, a. clutch part on the sub, leithand threads connecting the second mentioned clutch part with the sub, the clutch parts being operable to transmit rotation between the outer member and the weight element, and a righthand thread on the upper portion of the weight element to mate with a thread on a fishing string whereby the weight element may be freed by unthreading the said lefthand threads.

JESSE C. WRIGHT. 

